stalker



Jan. 31, 1956 E. A. STALKER 2,732,999

AXIAL FLOW ELASTIC FLUID TURBINE POWER PLANT, INCLUDING AN AXIAL FLOWRADIAL DIFFUSION COMPRESSOR Filed July 31, 1946 2 Sheets-Sheet l Jan.31, 1956 A. STALKER 2,732,999

AXIAL FLOW ELASTIC FLUID TURBINE POWER PLANT, INCLUDING AN AXIAL FLOWRADIAL DIFFUSION COMPRESSOR Filed July 31, 1946 2 Sheets-Sheet 2 AfeUnited States Patent AXIAL FLOW ELASTIC FLUID TURBINE POWER PLANT,INCLUDING AN AXIAL FLOW RADIAL DIFFUSION COMPRESSOR Edward A. Stalker,Bay City, Mich.

Application July 31, 1946, Serial No. 687,385

4 Claims. (Cl. 230--122) My invention relates to turbines andparticularly to internal combustion turbines commonly called gasturbines. It also relates to compressors employing a novel diifusionprinciple of compressing fluid.

An object of my invention is to provide turbine rotors or runnersadapted to be driven by jet reaction by jets passing betweensubstantially straight blades.

Another object is to provide an effective and simple compressoroperating by radial dilfusion.

Another object of my invention is to provide a means of cooling theblades wherein the blades pass successively into a cooling passage.

Other objects will appear from the description, drawings and claims.

I accomplish the above objects by the means illustrated in theaccompanying drawings in which- Figure 1 is a fragmentary axial sectionthrough a gas turbine along line 11 in Figure 2 according to the presentinvention;

Figure 2 is a front viewtof the turbine; Figure 3 is a fragmentarysection taken along line 3-3 in Figure 1 omitting the wall separatingthe turbine and 1953, entitled Prime Movers, which discloses acompressor rotor employing radial diffusion. In the earlier application,the claims are directed to a compressor rotor employing radial diffusiongenerally while in the present application the radial diffusion rotor isdisclosed in cooperation with a novel stator structure.

The gas turbine of this invention has a rotor whose blades aresubstantially straight in the directionof the flow between the blades.The blades pass successively through a hot motive gas and a coolingfluid. The straight blades and the mode of producing a force reactionbetween the fluid and the rotor leads to high efiiciency in the turbinepassage and the cooling passage.

In my patent application Serial No. 538,634, filed June 3, 1944, nowabandoned, I have described amethod of cooling blades where the bladespass successively out of a passage containing the flow of hot motive gasinto another passage containing a flow of cooling fluid. That 5 turbinehad conventionally curved blades which are very satisfactory forextracting energy from the motive gas but are wasteful of energy in thecooling passage. This is so because the curvature ofthe blades for theturbine side'is wrong for the cooling side or passage. It is wrong2,732,999 Patented Jan. 31,3956

for both possible conditions of operation of the cooling passage. Thatis, if the blades are correctly designed for the turbine passage, theywill be incorrect for pumping air through the cooling passage if themachine is operated to perform such a function. It will also be improperand of low efiiciency if it is desired to force air through the group ofblades in the cooling passage without doing work on the rotor. Some workwill always be done because of the curvature of the blades.

The present invention discloses a machine in which blading is providedwhich is just as efiicient in pumping air in the cooling passage as inoperating in the turbine passage.

The present invention also discloses blading which will absorb work inthe turbine passage but will do no work on the cooling air flow in thecooling passage if this mode of operating is desired. a

Conventional turbines of the curved blade type get a momentum reactiondirected peripherally because the blades curve the flow. In the turbineof the present invention the gas flow proceeds along the straight axisbetween the blades with increasing velocity, thereby creating a thrustalong the axis. A component of this thrust acts in the peripheraldirection to rotate the rotor.

Referring now particularly to the drawings, the turbine is 10. Airenters the inlet 12 and flows through the cooling passage 18 and the tworotors 14 and 16 into the collector 20. From it the flow goes via duct26 to the inlet collector 22 supplying the turbine passage 24. The

air is heated in duct 26 by the injection of fuel from nozzle 30. Thisis ignited by the spark plug 32 served with electricity from a suitablesource 31.

The case 40 of the turbine is divided into a turbine passage and acooling passage by the partitions 42, 44 and 46, shown in Figs. 1 to 5.The rotors pass their blades 50 and52 from the turbine passage 24successively into the cooling passage 18 and vice versa through the gapsbetween the walls.

Figure 4 shows the blades on the hub 64 and blades have been cut away orremoved at the top and bottom to show the partition 42.

The air is drawn into the cooling passage 18 by the pumping action ofthe blades therein. It is compressed and delivered to the turbinepassage for the production of power by the blades passing through theturbine passage.

The blades are formed in a special manner so as to be satisfactory andeflicient in both turbine passages. it will be observed from Figs. 1, 3and 5 that the blades 50 and 52 are thin elements of sharp or roundednose and sharp trailing edge. They are all fixed substantially parallelto each other on the rotor hubs, respectively 64 and 66. The passages 68and '70 between the blades are straight when viewed in a radialdirection as shown in Fig. 5 but are tapered when viewed in a peripheraldirection, as shown in Figs. 1 and 3.

The taper of the passage is formed in rotor 14 by the shape of the rotorhub 64 and the shroud ring 72, in rotor 16 by the shape of hub 66 andshroud ring 74. If desired all the tapers of the passages could beaccomplished in either the hubs or the shroud rings.

The passages between blades have a greater cross sectional area at exitthan at inlet so that they will pump air in the cooling passage. Howthis pumping action is accomplished is best shown by the vector diagramsin Fig. 5. Air flows axially in passage 18 as indicated by vector 80.Due to the movement of the blades there is a pcripheral relative vector82 giving the resultant vector 84 directed along the axis of passage 63.Since the passage 68 is expanding to a'larger exit, the velocity at theexit is reduced to the vector relative to the rotor. There is also theperipheral vector 92 equal to 82 but directed oppositely so that theresultant is 94. It will be clear that the air leaving the first rotorhas acquired an absolute net peripheral velocity component since the airwas originally moving only axially. Hence the blades have added energyto the air or a pumping action has taken place. if the vector 9%) hadbeen as long as 84, the air would have had only an axial velocity uponleaving the rotor and no pumping would have been accomplished.

The air from the rotor 14 is directed along the vector Q4 and the axesof the passages 70 of the rotor 16. The expansion of the air iscontinued in these passages and this rotor contributes further pumpingaction.

The passage 7% is divergent and continues the expansion of the gas inthe divergent portion of 68.

The passages 68 of the first rotor have a converging portion precedingthe diverging portion. This form is desirable in the turbine passage soas to produce a turning effort on the rotor.

The hot gases from duct 26 have sufficient temperature and pressure toachieve a supersonic velocity in passing through passages 68. The gasesenter at a subsonic velocity, attain sonic velocity at the throat, andbecome supersonic at the exit. Since the same mass of gas passes allsections of a passage 68 and the exit velocity is higher than the inletvelocity, there is a thrust acting on the tapered walls of the passage,namely on the shroud and the hub 64. This force 109 is indicated on thehub 64. It is obvious that this force has a component in the peripheraldirection and will turn the rotor in the direction 191. In order tobring the gas velocity to a supersonic velocity, it is necessary tofirst constrict the passage and t then expand it. However, where thepressures are not very high the rounding of the leading edges of thewalls may be suflicient for the inlet or converging portion.

Fig. 5 shows the vector diagrams for the motive gas flow. The axialvector is 102, the relative peripheral vector is 194 and the resultantis 106 directed along the axes of passages 68. At exitthe gas isdirected along the axes of the passages 70. Further expansion andincrease of velocity occur in these passages so that rotor 16 receives aturning force rotating rotor 16 in the direction 108.

Rotor 14 is fixed to shaft 119 while rotor 16 is fixed to shaft 112. Toeach can be attached a power load such as a propeller. The two rotorsand their respective shafts rotate in opposite directions.

Suitably contoured parts 130, 131 and 132 form the flow passages 18 and24 and serve to house the rotor shafts. They are supported from the caseby the walls 42, 44 and 46 respectively.

The walls such as 42, 44 and 46 are labyrinthed at 47 to reduce the flowof fluid from the turbine passage to the cooling passage and vice versa.See Figures 1 and 4.

The blades form radially directed walls for the blade passages and theseshould be substantially continuous from the inlet or front side of therotor to the exit or rear side of the rotor since the flow in eachpassage is rotors 15b and 152 are fixed to the same shaft 154. R0-

tors 150 and 152 are of the type respectively of rotors 1d and 16 ofFig. 1. Between them is interposed a stator having the tapering passages160 to reduce the supersonic velocity of the gas from'rotor 156 tosonic. It is then expanded again in the diverging passages 162 o'f'rotor152. See Figs. 6 and 7. T he entering resultant velocity vector in Fig.7 for the first stage is 179. Leaving, he

resultant velocity is 186. This is also the velocity entering passages16o. Leaving 160, the velocity is 182 giving with therelative peripheralvelocity 184 of 152 a resultant 186 directed along the axes of passages162. The tapered walls of the passages of rotors 159 and 152 receive athrust having a peripheral'component which turns them and shaft 154.

By expanding the rotor passages radially a far greater expansion'can beemployed than if the passages are ex panded in the peripheral direction.The latter requires surfaces which are curved in the peripheraldirection. This limits the amount of expansion since a flow trying toadvance against an adverse pressure gradient separates from the curvedsurface for a relatively small pressure rise. On the other hand withradial expansion of the passage no peripheral curvature of blades isrequired so that separation of the flow on them is avoided. Any tendencyto separate at the case wall is restrained by the centrifugal pressurewhich forces the flow against this wall as remarked above. At the inneror hub wall there is an outwardly increasing pressure gradientdue to thewhirl given the fluid and this also restrains the flow from separationfrom this wall. Consequently very great rates of expansion can be used.These conditions are borne out by test experience which show that forthe same efficiency and blade tip speeds the pressure rise is aboutthree times that of rotor passage employing peripheral expansion.

It is to be noted in Fig. 6 that the outer peripheral wall of eachpassage 162 departs from the axis of rotation at a greater rate than theinner peripheral wall. Since centrifugal force will throw the passagefluid against the outer wall, the fluid will not tend to separate fromthe wall even for a very large angle of divergence. This feature isparticularly important when the rotor passages are acting to pump fiuidsince it makes possible a short and light weight rotor.

In still another form of the invention shown in Fig. 8 the rotor bladesare designed to provide no pumping action in the cooling passage. Thecooling air is forced through the cooling passage 20% by an externalsource 201 of compressed air delivered by the duct 202. The flow throughthe turbine or hot fluid passage 24 is supplied from a suitable source208 by duct 203. The cold flow is exhausted through exit 264 and the hotflow through exit 205.

In orderto do no pumping in the cooling passage 200, the passages 266between the blades on the rotor hub 210 are made with equal crosssectional areas at inlets and exits. The blades and hub constitute therotor 211 mounted on shaft 213. The stator passages 214 are preferablymade of increasing cross sectional area.

Referring to Fig. 9 the axial velocity of the gas in the turbine side isthe subsonic velocity 220, the relative peripheral velocity is 222 andthe resultant subsonic velocity is 224. Upon leaving the rotor thevelocity is supersonic of magnitude shown by vector 226. The peripheralvelocity vector is 228 giving a velocity vector 230 relative to thestator 215. Since the state mass passes the inlet and the exit of eachpassage 206 there has been an increase in the momentum at exit over thatat the inlet so that there is a thrust 232 which has a component turningthe rotor. The increase of momentum will always be present if the inletvelocity is subsonic and the exit velocity is supersonic, even throughthe inlet and exit areas are equal.

On the cool fluid side the axial velocity vector is 240 and theperipheral vector is 242 of the same magnitude as vector 222. Theresultant velocity at entrance to the rotor passages is the subsonicvector 244. The magnitude of the vector 25a leaving the rotor is thesame as that of vector 244 because the areas of inlet and exit areequal. Vector 251 is equal to vector 240. The velocity vector for thefluid leaving the exit 265 is 252. Each rotor passage lies between thefront and rear faces of the rotor or rotor stage. :Rotor passagesrotate-in whole with the rotor.

A rotor-stage is comprised of rotor blades defining passages directing aflowof the gas from one side of the rotor to the other or from one groupof stationary vanes to another.

The rotor .passages having a converging portion succeeded by a divergingportion are suited to receive elastic fluid at either subsonic orsupersonic velocity and dis charge said fluid at supersonic velocity.

It will also be clear that I have provided a novel and useful gasturbine which can operate at high temperatures because of the eflectiveblade cooling.

While I have illustrated a specific form of this invention it is to beunderstood that I do not intend to limit myself to this exact form butintend to claim my invention broadly as indicated by the appendedclaims.

I claim:

1. In combination in an axial flow elastic fluid compressor forincreasing the pressure of a fluid flow therethrough, a rotor mountedfor rotation about an axis and having a plurality of blades, said rotorhaving passages therethrough between adjacent blades from front to back,said passages being set peripherally obliquely to said axis and havingan exit greater than the inlet in radial depth and cross-sectionalarea,the radial depth of each said inlet passage at the inlet end thereofbeing less than the radius from said axis to the radially inward side ofeach said passage at the inlet end of said passage, said exit facingrearward to discharge fluid rearward in the general direction of saidaxis, said rotor passages being arranged such that the angle between theforward portion of each blade and said axis is at least as great as thatbetween the aft portion thereof and said axis, the axial length of thediverging portion of said rotor passages being not greater than themaximum radial depth thereof to provide a substantial angle ofdivergence between the inner and outer walls of said passage, the radiifrom said axis to the tips of said blades substantially increasing inthe downstream direction, and a stator structure positioned adjacentsaid rotor on the downstream side thereof, said structure having a flowpassage therethrough of rearwardly decreasing radial depth and crosssectional area measured normal to said axis, said passage being adaptedto receive fluid thereinto from said rotor passage.

2. In combination in an axial flow elastic fluid compressor forincreasing the pressure of a fluid flow therethrough, a rotor mountedfor rotation about an axis and having a plurality of blades, said rotorhaving passages therethrough between adjacent blades from front to back,said passages being set peripherally obliquely to said axis and havingan exit greater than the inlet in radial depth and cross sectional area,the radial depth of each said inlet passage at the inlet end thereofbeing less than the radius from said axis to the radially inward side ofeach said passage at the inlet end of said passage, said exit facingrearward to discharge fluid rearward in the general direction of saidaxis, said rotor passages being arranged such that the angle between theforward portion of each blade and said axis is at least as great as thatbetween the aft portion thereof and said axis, the axial length of thediverging portion of said rotor passages being not greater than themaximum radial depth thereof to provide a substantial angle ofdivergence between the inner and outer walls of said passage, the radiifrom said axis to the tips of said blades substantiallyincreasing in thedownstream direction, and a stator structure positioned adjacent saidrotor on the downstream side thereof, said structure having a flowpassage therethrough of decreasing radial depth in the downstreamdirection, said passage being adapted to receive fluid thereinto fromsaid rotor passage, the inner peripheral wall of said stator extendingradially outward and rearward with its rear edge further out radiallythan the front edge thereof.

3. In combination in an axial flow compressor having an inlet duct forreceiving a fluid flow and for the compression and impulsion of saidfluid flow therethrough with increase in the static pressure thereof, acompressor rotor mounted for rotation about an axis, said rotor hav inga plurality of peripherally spaced streamlined blades defining aplurality of passages extending through from the front to the back ofsaid rotor, the shape of said rotor blades being such that the anglebetween the forward portion of each blade and said axis is at least asgreat as that between the aft portion thereof and said axis, said bladesbeing movable across the cross section of said duct, each said passagehaving increasing radial depth and cross-sectional area in thedownstream direction with the cross-sectional area of the exit of eachpassage being greater than the inlet area-thereof with resultant staticpressure rise in the fluid flow, the axial length of the divergingportion of said rotor passages being not greater than the maximum radialdepth thereof to provide a substantial angle of divergence between theinner and outer walls of said passage, the radii from said axis to thetips of said blades substantially increasing in the downstreamdirection, a stator structure positioned adjacent said rotor on thedownstream side thereof, said structure having a plurality of statorpassages therethrough adapted to receive fluid from said rotor, eachsaid stator passage having a smaller exit than inlet cross-sectionalarea, and another rotor positioned adjacent said structure on thedownstream side thereof, the last said rotor having a plurality ofpassages therethrough of increasing radial depth and cross-sectionalarea in the downstream direction and adapted to receive fluid from saidstator structure passages, and means to rotate said rotors to impel aflow of fluid through said duct and passages.

4. In combination in an axial flow compressor for increasing thepressure of a fluid flow therethrough, a rotor mounted for rotationabout an axis, said rotor having a plurality of blades and havingpassages therethrough between adjacent blades from an inlet at the frontto an exit at the back thereof, said passages being set obliquely tosaid axis, said exit having a greater radial depth and area than saidinlet, the radial depth of each said inlet passage at the inlet endthereof being less than the radius from said axis to the radially inwardside of each said passage at the inlet end of said passage, said exitfacing rearward to discharge fluid rearward in the general direction ofsaid axis, said rotor passages being shaped such that the angle betweenthe forward portion of each said passage and said axis is at least asgreat as that between the aft portion thereof and said axis, the axiallength of the diverging portion of said rotor passages being not greaterthan the maximum radial depth thereof to provide a substantial angle ofdivergence between the inner and outer walls of said passage, the radiifrom said axis to the tips of said blades substantially increasing inthe downstream direction, a stator structure positioned adjacent saidrotor on the downstream side thereof, said structure having a flowpassage therethrough of rearwardly decreasing cross-sectional area withits exit area less than its inlet area and adapted to receive fluidthereinto from said rotor passage.

References Cited in the file of this patent UNITED STATES PATENTS461,051 Seymour Oct. 13, 1891 741,940 Shepard Oct. 20, 1903 1,307,864Jones June 24, 1919 1,390,733 Spies Sept. 13, 1921 1,447,554 Jones Mar.6, 1923 1,518,501 Gill Dec. 9, 1924 1,525,853 Corthesy et a1 Feb. 10,1925 1,601,614 Fleming Sept. 28, 1926 2,008,520 Soderberg July 16, 19352,065,974 Marguerre Dec. 29, 1936 2,258,793 New Oct. 14, 1941 2,419,689McClintock Apr. 29, 1947 2,435,236 Redding Feb. 3, 1948 FOREIGN PATENTS386,039 Great Britain Jan. 12, 1933 439,773 Great Britain Dec. 13, 1935

